Purpose:
Invasive fluorescein angiography with ectatic perifoveal capillaries and an area of diffuse leakage in the late phase angiography confirms the challenging diagnosis of type 2 macular telangiectasia (type2-IMT). Spectral narrowing of the fundus illumination and confocal imaging is known to enhance contrast and resolution of details in the fundus and to suppress stray-light. We determined the characteristics of type2-IMT using non-invasive monochromatic blue and infrared reflectance imaging with a confocal laser scanning ophthalmoscope (cSLO).
Methods:
14 eyes were investigated by means of ophthalmoscopy, digital fundus photography and OCT-imaging. A cSLO (HRA2, Heidelberg Engineering, Dossenheim, Germany) was used for fluorescein angiography and fundus reflectance images that were acquired at 488nm (blue) and 820nm (infrared).
Results:
Within the macular area of angiographic late stage leakage, blue-reflectance disclosed bright and clearly demarcated oval areas. Such increased reflectance was present even in areas of low grade leakage. Intraretinal pigment or crystalline deposits were clearly highlighted by this imaging mode. In contrast, infrared-reflectance showed a predominantly darker, well demarcated oval area in eyes with late disease stages (n=3; figure A). In earlier stages, a subgroup of eyes (n=9) showed a patchy macular appearance with increased and decreased reflectivity within the area of macular leakage (figure B) whereas another subgroup was undistinguishable from normal (n=2).
Conclusions:
There is good topographic correspondence between leakage in late stage angiography and changes in infrared and red-free reflectance.Short wavelengths are predominantly reflected by the superficial retinal layers. Therefore, increased reflectance using blue light could be a result of topographic alterations of the retinal surface caused by structural changes in the superficial retinal layers. The source of the variable alterations in infrared reflectance imaging remains to be determined.The two imaging modalities may be useful as non-invasive diagnostic tools in type2-IMT.
Keywords: imaging/image analysis: clinical • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • macula/fovea